Inspector Edgardo Bernardo, police chief in Pilar town in Bataan, said many of the dolphins were found in shallow water and some had come ashore, including three in a bad condition due to wounds.

Malcolm Sarmiento, head of the fisheries and aquatic resources bureau, said experts were studying whether an underwater quake had disoriented the animals or the pack of dolphins followed a sick leader.

“Many strange things are happening in our oceans now and we still don’t have any explanation for these occurrences,” Sarmiento said.